Design of corrosion-resistant absorbers with a core @ compact film structure based on the “dissolution-redeposition” theory

Abstract

Chemical stability is the key factor of magnetic metal powder absorbers for their practical applications in the marine environment. Herein, a strategy of phosphating conversion coating (PCC) preparation based on the “dissolution-redeposition” theory which can regulate the surface dissolution reaction and deposition process of metal powder absorber was constructed reasonably. The TA/pH value of the phosphate conversion solution could be adjusted to reduce the hydrogen evolution rate and increase the nucleation rate of CaHPO4 to prepare compact PCC with a certain thickness on the surface of iron powder. Results show that among the different samples, the sample fabricated in TA/pH = 11.37 solution has the best corrosion resistance with the lowest corrosion current density (Icorr = 0.12 μA/cm2) and the highest corrosion potential (Ecorr = -0.453 V) due to the excellent compactness of PCC, and best microwave absorption performance due to the retained conductivity loss and improved impedance matching of the relatively thin thickness of PCC. The minimum reflection loss was -51.31 dB at 16.6 GHz and the effective bandwidth (RL < -10 dB) up to 5.4 GHz with a matching thickness of 2.28 mm. This work provides a useful reference for the design of integrated materials with microwave absorption and corrosion protection for practical applications.